2 Engines, each with 500k miles. Difference? The oil: one synthetic, one conventional

[GladiatorPilot23]

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[Hootbro]

Heads-up, it leans very heavily towards the benefit of synthetic.

Not saying a synthetic is not better, but they still got 500K miles out of it running it with conventional.

 

[HankB]

I started using Mobil One in my air cooled Porsche in the early nineties because the engine literally inhaled anything else (including Castrol), and have continued with every one since including the present P4S. The daily drivers along the way got it as well, just because.

For the boat (twin Volvo D6- 600 diesels) that are both super and turbo charged we use Volvo Penta branded synthetic only because it’s what the first owner of the boat used and it works. We put about 100 hours on them a season and do one change a year, and while painful (10 gallons), there is no consumption so it’s win win.

For the Glad, it got whatever the dealer put in it during the wave freebies, and once off warranty i will probably switch it to Mobil One, just to only have one jug in the garage for top offs (wife’s SQ5 also uses it), more or less “just because”.

Bottom line I really don’t see the same need as fifty years ago.

 

[Greg_L]

In my engine building racing days we used to use miniscule oil control rings for no drag and the lightest Royal Purple we could get. I think it was called "Lite 11" back then and it ran like water. It was like 0W-0 lol. Shockingly thin. We'd instruct the driver "do not look at the oil pressure gauge. Ignore it" because at idle it would read no pressure - too thin to even budge the gauge. Normally that would be cause for concern but not with these engines - they were built tight and perfect and they never showed any adverse bearing wear from the super light oil. They were also drag engines so you know, they got rebuilt a lot. But still, nothing your Jeep engines can do even comes close to the extremes of a 1000 hp naturally aspirated Big Block Chevy turning 9000rpm, so don't be so picky. Use good oil, whatever you want, and go drive your thing.

 

[DrewsJT]

Ever since flat tappet cams went away in production engines, we don't really need conventional oil anymore. We don't need the zinc and other additives that made conventional oil so good for what it did. Youtube vids and internet opinions don't matter - conventional oil was amazing for it's day and the engine's of it's day. Do we need it now? Nah. Not because the oil is the problem, but because engines are the problem.

Just my opinion, but I don't agree about the zinc. Look at all the rocker tip, lifter and cam issues that stellanis/gm/ford are having

 

[Reddog]

Ever since laying hands on my Gladiator I have changed my own oil and have always used AMSOil 0W20 because I believe it to be the best of the synthetics for the longevity of my engine. Is it? That's debatable. Is synthetic better than conventional oil? There are a gazillion opinions out there ranging from "absolutely" to "it makes no difference as long as you change regularly". I came across this video, it is the most objective one I've seen and virtually eliminates all variables... as well as the "opinion" factor out of the equation.

Heads-up, it leans very heavily towards the benefit of synthetic.

Sharing it with you fine folks.

Yes, the video tries but they are comparing apples and oranges. Personally, I think if you change your oil regularly at, say, 3-4K miles, they both probably do a good job and measurable differences are negligible. If you go farther between changes then I think synthetic has a real advantage. The synthetic is much better suited for high heat engines like the newer cars experience too. You aren't going to go 8-10K between changes with conventional oil without added engine wear. Synthetic oil has certain adhesion properties that conventional doesn't and that, according to a rep for Mercedes Benz, is why newer engines start cold and idle faster until warmup without adding to wear. Might explain why Jeep 3.6 gas engines have a filter that drains back after shutdown and starts cold with a split second delay until oil pressure fills the housing. But who knows. Looking at the odd or problematic features (in my experience) the JT can exhibit, I sometimes wonder if any Stellantis engineers know what they are doing. I don't know the real answer here but I believe the synthetic oil is a better product than conventional oil over all.

 

[Greg_L]

Just my opinion, but I don't agree about the zinc. Look at all the rocker tip, lifter and cam issues that stellanis/gm/ford are having

That could be the machining process or assembly specs. Usually once contact parts are worn in and seated successfully they don't have too much problem living a happy life. In the old days the first 20 minutes or so of a camshaft's life meant EVERYTHING. If those lifters and cam lobes didn't get to know each other peacefully then that cam was not gonna be long for the world. I'm talking failure within a few days. How did they survive? They were machined to survive and all they lived off of was mostly splash from the crankshaft. If you made it past that nerve-wracking and ear damaging 20 minute 3000 rpm break in and nothing cratered then the odds were very good that you'd have a long lasting engine....at least as far as the valve train goes. Simple flat-tappets and dinosaur oil got it done. Now with rollers and/or OHCs that particular type of break-in is no longer necessary, nor is the oil that made it all happen.

 

[DrewsJT]

That could be the machining process or assembly specs. Usually once contact parts are worn in and seated successfully they don't have too much problem living a happy life. In the old days the first 20 minutes or so of a camshaft's life meant EVERYTHING. If those lifters and cam lobes didn't get to know each other peacefully then that cam was not gonna be long for the world. I'm talking failure within a few days. How did they survive? They were machined to survive and all they lived off of was mostly splash from the crankshaft. If you made it past that nerve-wracking and ear damaging 20 minute 3000 rpm break in and nothing cratered then the odds were very good that you'd have a long lasting engine....at least as far as the valve train goes. Simple flat-tappets and dinosaur oil got it done. Now with rollers and/or OHCs that particular type of break-in is no longer necessary, nor is the oil that made it all happen.

But the old oil had tons of zddp break-in was important but they wouldn't last with out the zinc, that's why they added it in the 1930's. Even today if you want to kill a 70's flat tappet motor, run today's gas oil. That's why most hotrodders either add zddp or run diesel oil.
It just seems strange that they've been taking the zinc out a little at a time and every manufacture(gm,stellanis,ford& toyota) all have valve train "machining" issues, don't ya think?
I'm not a chemists but I am a 40 machinery mechanic that worked on steam/gas turbines, pumps and compressors from ground up rebuilds to alignments and vibration testing.
Not bragging but I'm not a dummy.
Like I said earlier, just my opinion.

 

[DrewsJT]

Yes, the video tries but they are comparing apples and oranges. Personally, I think if you change your oil regularly at, say, 3-4K miles, they both probably do a good job and measurable differences are negligible. If you go farther between changes then I think synthetic has a real advantage. The synthetic is much better suited for high heat engines like the newer cars experience too. You aren't going to go 8-10K between changes with conventional oil without added engine wear. Synthetic oil has certain adhesion properties that conventional doesn't and that, according to a rep for Mercedes Benz, is why newer engines start cold and idle faster until warmup without adding to wear. Might explain why Jeep 3.6 gas engines have a filter that drains back after shutdown and starts cold with a split second delay until oil pressure fills the housing. But who knows. Looking at the odd or problematic features (in my experience) the JT can exhibit, I sometimes wonder if any Stellantis engineers know what they are doing. I don't know the real answer here but I believe the synthetic oil is a better product than conventional oil over all.

I would like to see that same test but with the Amsoil doing 10k oil changes with 5k filter change vs. 3-4k dino oil filter change.
Them you'd see the advantage of good synthetic oil $$

 

[Reddog]

I would like to see that same test but with the Amsoil doing 10k oil changes with 5k filter change vs. 3-4k dino oil filter change.
Them you'd see the advanta teardown the ge of good synthetic oil $$

Yeah, but part of me thinks everyone needs to recognize that conventional and synthetic oils are two different things and stop trying to compare them. Back in my early years I raced 396 and 427 Chev big blocks. These engines were driven very hard and never suffered an oil related failure. I used the same Valvoline oil in my daily drivers and never had an issue with them. I changed oil religiously at 3000 miles in the daily drivers. On tear down, they were clean as a whistle. The secret to long engine life is regular oil and filter changes. I think if you use the type and weight of oil the manufacturer specified, you are fine. As to how long you should go between changes, that will never be answered to everyone's satisfaction. I don't know what the number is but it's closer to 4000 miles than it is to 10,000 miles if you are keeping your vehicle long term. My sons now has my LS3 converted JK and it has 160,000 miles on it and has always been serviced at 4000 miles using Mobil One full synthetic. It doesn't burn a drop of oil and other than changing sparkplugs he has never had any engine part failure. Part of long engine life is proper maintenance and part of it is operator head-space and timing. Have a great Christmas.

 

[DrewsJT]

Yeah, but part of me thinks everyone needs to recognize that conventional and synthetic oils are two different things and stop trying to compare them. Back in my early years I raced 396 and 427 Chev big blocks. These engines were driven very hard and never suffered an oil related failure. I used the same Valvoline oil in my daily drivers and never had an issue with them. I changed oil religiously at 3000 miles in the daily drivers. On tear down, they were clean as a whistle. The secret to long engine life is regular oil and filter changes. I think if you use the type and weight of oil the manufacturer specified, you are fine. As to how long you should go between changes, that will never be answered to everyone's satisfaction. I don't know what the number is but it's closer to 4000 miles than it is to 10,000 miles if you are keeping your vehicle long term. My sons now has my LS3 converted JK and it has 160,000 miles on it and has always been serviced at 4000 miles using Mobil One full synthetic. It doesn't burn a drop of oil and other than changing sparkplugs he has never had any engine part failure. Part of long engine life is proper maintenance and part of it is operator head-space and timing. Have a great Christmas.

On my jt it's north of 6k by the cb change.
As for the changes I totally agree
Amsoil says 25k I change mine at 6k and filters at 3k

 

[Greg_L]

But the old oil had tons of zddp break-in was important but they wouldn't last with out the zinc, that's why they added it in the 1930's. Even today if you want to kill a 70's flat tappet motor, run today's gas oil. That's why most hotrodders either add zddp or run diesel oil.
It just seems strange that they've been taking the zinc out a little at a time and every manufacture(gm,stellanis,ford& toyota) all have valve train "machining" issues, don't ya think?
I'm not a chemists but I am a 40 machinery mechanic that worked on steam/gas turbines, pumps and compressors from ground up rebuilds to alignments and vibration testing.
Not bragging but I'm not a dummy.
Like I said earlier, just my opinion.

Nah I agree with you. I just don't know many issues issues these engines actually have, or if it's the oil's fault. There's about a thousand other variables that can cause problems before it's the oil's fault.

 

[Stan H]

I watched the video the build up is impressive. But they both made it the distance.

 

[Riverdog]

This debate is old and has good points on either side. Some say early synthetics caused bearings to slide rather that roll in some cases, but overall it's a better quality oil. My biggest complaint is people who think...because synthetic costs more , and is better then I can go 10k miles before changing it. I'm old school and grew up working on old Jeeps and Harleys, and always used cheap oil but changed it every 2500 miles religiously. If the intervals are the same, synthetic has some advantages for sure. But I'd still rather buy a used car that had conventional oil changes every 2500 miles than synthetic every 10k. But I also change vehicles every 6 months to a year so I've never needed anything to last

 

[BourbonRunner]

This debate is old and has good points on either side. Some say early synthetics caused bearings to slide rather that roll in some cases, but overall it's a better quality oil. My biggest complaint is people who think...because synthetic costs more , and is better then I can go 10k miles before changing it. I'm old school and grew up working on old Jeeps and Harleys, and always used cheap oil but changed it every 2500 miles religiously. If the intervals are the same, synthetic has some advantages for sure. But I'd still rather buy a used car that had conventional oil changes every 2500 miles than synthetic every 10k. But I also change vehicles every 6 months to a year so I've never needed anything to last

TBF, some clever (and repetitive) marketing from Jiffy Lube back in the day convinced most folks that 3000 miles/3 months was the "right" change interval. Reality is that even with dino juice, 5k was perfectly fine for the majority of non-extreme use cases and 3K was wasteful, especially since the manufacturers recommended longer intervals. Jiffy Lube was sued multiple times over that.

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